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The integration of CMOS electronics with MEMS (micro-electro-mechanical systems) is attractive because it allows MEMS components to be co-located with their associated control and signal processing circuits. However, monolithic integration of electronics with micromechanics generally involves a high initial investment, and can be difficult because of process and material incompatibilities. One approach which avoids some of these issues, and is applicable to low-temperature metal MEMS processes, is to post-process IC (integrated circuit) dies that have been implanted in a carrier wafer. We have developed a process of this type in which CMOS dies are embedded in a 100 mm-dia BSOI (bonded silicon on insulator) carrier. Deep reactive ion etching (DRIE) is used to form die cavities in the device layer, stopping at the buried oxide. The cavity depth is finely adjusted by thinning the device layer so that top surface …